He was a swinger. he did it for the orgies in the 1960s.
Manson ran in Hollywood circles. He knew musicians beyond just the Beach Boys. He also ran in drug circles.
Bob Crane filmed his own orgies.
Rob Lowe videotaped his activities.
Pamela and Tommy Lee videotaped their activities.
Chuck Berry videotaped his activities.
I don't claim that such a film exists or that the police hold it, but do not find the possibility to be “outrageous”.
PS. Anton LeVay was a police crime photographer awhile.